Hatiora

Hatiora gaertneri

Hatiora gaertneri (Regel) W. Barthlott.
Engl.: christmas cactus, easter cactus.
Bot. syn.: Epiphyllum russellianum var. gaertneri Regel, Rhipsalidopsis gaertneri (Regel) Moran, Schlumbergera gaertneri (Regel) E. Britton & A. Rose.

I have no articles for this botanical term, but there might be some for the next level down (if found).